The present invention relates to a continuously variable transmission (CVT).
An example of a continuously variable transmission is shown in U.S. Pat. No. 6,676,560 ('560 patent), issued to Terry Buelna on Jan. 13, 2004. The continuously variable transmission has many potential applications such as an automotive transmission, an industrial drive or a wind turbine drive train. One of the benefits of the continuously variable transmission is that the drive ratio from input to output is infinitely variable throughout its range. The drive ratio is limited only by the relative sizes of the drive components.
As discussed in the '560 patent, the drive ratio from input to output is varied by pushing a first set of rollers closer to a main shaft. This has the effect of traversing a second set of rollers further away from the main shaft. The relative positions of the first and second sets of rollers determine the drive ratio. Since the first and second sets of rollers are frictionally engaged to a plurality of discs, the first and second sets of rollers may be positioned at any distance from the main shaft. Hence, the drive ratio may be fine tuned based on the requirements of the overall device in which the continuously variable transmission is used.
During operation of the continuously variable transmission, the drive ratio from input to output is varied. When either the first or second sets of rollers is pushed toward the main shaft, the forces imposed on the rollers and discs may be imbalanced thereby causing various issues (e.g., efficiencies, misalignment, etc.) in the continuously variable transmission. As such, there is a need in the art for an improved continuously variable transmission.